In the years since the Second World War, scientists of many stripes have calculated the probability of other life existing somewhere in the universe. With around 125 billion galaxies estimated through Hubble telescope observation, one estimate states there should be as many as 6.25×109 (billion) inhabitable planets in the universe. The law of averages says some of them should have life, and even civilizations.
OK ... so where are they?
In the short time that scientists have searched for evidence of extraterrestrial life, nothing has been found. The paradox, the difference between estimates of inhabitable planets and the utter lack of evidence of such life, is called the Fermi Paradox, after Enrico Fermi who posed the question in the 1950s.
There are many theories seeking to answer the paradox. Perhaps one of the simplest is the “rare earth” theory, meaning that estimates of habitable planets in the universe are flawed. Our planet is the only one, or one of the few, that can support life. Hard to believe considering the billions of stars.
Another theory is that “intelligent life tends to destroy itself.” This theory proposes that civilizations are by nature violent, and they never progress far enough scientifically to leave any evidence that they existed.
Then there is the “galactic disaster” theory. This includes a number of natural disasters such as comet or asteroid strikes, or something as unlikely as a sun exploding. Civilizations, this theory states, don’t leave evidence because nature destroys them on a regular basis.
Yet another theory is called the “impossible communication” theory. This proposes that we, human beings, and the alien races that exist are so different that even when we receive evidence of their existence, and vice versa, we don’t realize it. Perhaps their bodies are pure energy and they communicate with blue shift and red shift light technology. Who knows?
One of the most dramatic theories is the “super-predator” theory. Civilizations don’t communicate because there is one civilization above all that intentionally seeks out and destroys the others, and those that aren’t destroyed stay silent out of fear. Perhaps the super-predator is on its way to Sol 3 (us) right now.
The “zoo” theory states that, yes, alien civilizations are watching us right now. They’ve chosen not to contact us for whatever reason. Perhaps we are too violent, and we have not developed enough and they’re waiting for us to evolve socially before contact is made. When you look at the violence around our world today, this theory actually makes perfect sense.
Then there is the “spread across time” theory. Yes, there have been thousands of civilizations, but each was separated by millions of years of time. The next civilization won’t pop up for millions more.
Regardless, I tend to keep in mind something that astrophysicist Carl Sagan said about the search for alien life.
“Some wonder if we are alone. We’re not alone. We have each other.”
Stu Salkeld is the editor of the St. Albert Gazette. No paradox prevents readers from contacting him at [email protected].
